Simulink Engine Interaction with System Object Methods
Simulink Engine Phases Mapped to System Object Methods
This diagram shows a process view of the order in which the MATLAB System block invokes System object™ methods within the context of the Simulink® engine.

Note the following:
Simulink calls the
stepImpl,outputImpl, andupdateImplmethods multiple times during simulation at each time step. Simulink typically calls other methods once per simulation.The Simulink engine calls the
isOutputFixedSizeImpl,getDiscreteStateSpecificationImpl,isOutputComplexImpl,getOutputDataTypeImpl,getOutputSizeImplwhen using propagation methods.Simulink calls
saveObjectImplandloadObjectImplfor saving and restoring the model operating point, the Simulation Stepper, and Fast Restart.Default implementations save and restore all properties with public access, including
DiscreteState.